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Full text of "The Morphology And Evolution Of The Apes And Man"

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THE SKELETON AND TEETH              139
triangular on cross section; the flexure at the acromial end is less marked than in Man, but the acromial end is broader and flatter.
Scapula.—In the Gibbons the scapula is narrow* with large coracoid and acromion processes; and the spine divides the dorsum into nearly equal supraspinous and infraspinous fossae. In the Orang it is nearly as wide as in Man, but the acromion is narrower and longer, and the spine is more vertical. The Chimpanzee has a long, narrow scapula, with strong coracoid and acromion processes; it is, therefore, similar to that of the Gibbon, but the suprascapular notch is narrower and deeper. The Gorilla has a broader scapula than the Chimpanzee, but it has no marked suprascapular notch; its spine is more oblique than in Man, and the coracoid process is longer and stronger. The glenoid fossa looks more obliquely upwards in the Gorilla than in Man.
Humerus.—In the Gibbons tHe humerus, like the radius and ulna, is a long bone with a delicate shaft and two expanded extremities. The intertubercular sulcus is well defined, but the pectoral crest is poor. No supra-condylar foramen is present in young animals. Such foramina are present in the Orang, and in full-grown Gorillas, but are absent in the Chimpanzee. In the African Apes the humerus is strong, with well-developed crests, but the deltoid eminence is poor, whereas it is
verv well marked on the bone in Man.    The lower end
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of the bone is wider than the upper end, it being one and a half times as broad as the upper end in the Chimpanzee.      The back of  the   shaft  is  grooved for  the musculo-spiral nerve in the Chimpanzee and Gorilla, Radius and Ulna.—In the Gibbons these bones are